B12 & Fatigue in Vegetarians

Strict vegetarians may need to take a vitamin B-12 supplement.

Only about 2 percent of the general population in the United States is deficient in vitamin B-12, reports the Centers for Disease Control and Prevention. However, if you're a strict vegetarian, you may be more likely to suffer from low vitamin B-12 levels since the nutrient is only naturally present in animal-based foods. Vitamin B-12 deficiency can cause a number of symptoms, including fatigue. Vegetarians should speak to their doctor about ways to increase their vitamin B-12 intake if they aren't getting enough.

Vitamin B-12 Deficiency

A healthy adult man or woman between 19 and 50 years old needs at least 2.4 micrograms of vitamin B-12 each day in order for the nervous and immune systems to function properly, and for the body to produce DNA, RNA and red blood cells. Without enough vitamin B-12, you may develop pernicious anemia, a condition characterized by a lower than normal number of red blood cells. People with pernicious anemia suffer from fatigue because they don't have enough oxygen in their bloodstream. They may also experience headaches, chest pain, dizziness and trouble breathing. According to the National Heart, Lung and Blood Institute, strict vegetarians are at a greater risk for developing pernicious anemia.

Vegetarian Vitamin B-12 Requirements

The Linus Pauling Institute says that vegetarians and vegans who don't consume any meat, eggs or milk have a higher need for vitamin B-12 than adults who do include animal-based products in their diet to ensure adequate intake and to prevent pernicious anemia. This is especially important for pregnant and lactating vegetarian women, cautions the Vegetarian Resource Group. All vegetarians should aim to consume between 6 to 30 micrograms of vitamin B-12 each day.

Vegetarian Sources of Vitamin B-12

If you're an lacto-ovo vegetarian -- a vegetarian who doesn't eat seafood, poultry or meat but does consume dairy products and eggs -- you'll be able to fulfill much of your vitamin B-12 through your diet alone. The same is true for pescatarians, or vegetarians who eat no other animal products other than fish. A 3-ounce serving of cooked fish like salmon provides 2.4 micrograms of vitamin B-12. A vegetarian who doesn't include any animal-based foods in his diet can obtain vitamin B-12 from fortified soy milk or ready-to-eat breakfast cereals. Nutritional yeast is also a source of vitamin B-12.

Vitamin B-12 Supplementation

Vegetarians should talk to their doctor about taking vitamin B-12 supplements, particularly vegetarians who are over 50 years old, recommends the University of Maryland Medical Center. Vitamin B-12 supplements, which are sometimes labeled under the name cobalamin, are available as tablets, lozenges and capsules, as well as nasal sprays. Supplementation with vitamin B-12 is not associated with adverse side effects, but it may interfere with the function of antibiotics such as tetracycline, metformin, anti-seizure drugs and proton pump inhibitors like lansoprazole. Ask your physician to help you determine an appropriate daily dosage.

About the Author

Michelle Kerns writes for a variety of print and online publications and specializes in literature and science topics. She has served as a book columnist since 2008 and is a member of the National Book Critics Circle. Kerns studied English literature and neurology at UC Davis.